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A Selective Direct Aldol Reaction in Aqueous Media Catalyzed byZinc–Proline
Author(s) -
FernandezLopez Ruben,
Kofoed Jacob,
Machuqueiro Miguel,
Darbre Tamis
Publication year - 2005
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200500352
Subject(s) - aldol reaction , chemistry , dihydroxyacetone , acetone , catalysis , aqueous medium , proline , stereoselectivity , aqueous solution , enantiomeric excess , organic chemistry , enantiomer , enantioselective synthesis , organocatalysis , amino acid , biochemistry , glycerol
The Zn–proline complex is shown to catalyze the aldol reaction of acetone and a wide range of arenecarbaldehydes in aqueous media, accepting even deactivated arenecarbaldehydes such as methoxybenzaldehydes in good yields. Enantiomeric excesses of up to 56 % could be obtained with 5 mol‐% of the catalyst at room temperature, and up to 66 % at –15 °C. The aldol reaction is regio‐ and stereoselective with hydroxyacetone (moderate yields) and dihydroxyacetone (excellent donor, 80–90 % yields with 5 mmol‐equiv.). Plausible mechanisms for the reaction are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)